Anti-corrosive mixture and coating substances containing said anti-corrosive mixture

ABSTRACT

A corrosion inhibiting mixture comprising
     (A1) corrosion-inhibiting pigments,   (A2) amorphous silica modified with metal ions, and   (A3) at least one compound of the general formula I:
 
M n (X) m   (I)
       in which the variables and indices have the following meanings:   M is at least one central atom selected from the group of Lewis acceptors,   X stands for Lewis donor ligands having at least one bridging atom selected from elements of main groups 5 and 6 of the periodic table of the elements,   n is from 1 to 500, and   m is from 3 to 2000;
 
coating materials comprising said mixture and their use as coil coating materials.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Phase Application of Patent ApplicationPCT/EP03/00436 filed on 17 Jan. 2003, which claims priority to DE 102 02545.2, filed on 24 Jan. 2004.

The present invention relates to a novel corrosion inhibiting mixture.The present invention also relates to the use of the novel corrosioninhibiting mixture for the corrosion protection of coils. The presentinvention further relates to novel coating materials, especially coilcoating materials, which comprise the novel corrosion inhibitingmixture. The present invention relates not least to the use of the novelcoating materials, especially the coil coating materials, for producingcorrosion protection coatings for coils.

Coil coating materials, which are applied predominantly by rollerapplication using contrarotating rolls to steel coils (strips or longsheets), especially galvanized steel coils, or aluminum coils, areknown. Since the processing of the metal does not take place until afterthe coating process, the coatings need to have extremely high mechanicalintegrity. Typical drying times are from 20 to 40 seconds at a metaltemperature of from 200 to 260° C. The coated coils are used customarilyin the architectural sector for producing ceiling and wall elements,doors, pipe insulations, roller shutters or window profiles, in thevehicle sector for producing paneling for caravans or truck bodies, andin the household sector for producing profile elements for washingmachines, dishwashers, freezers, fridges or ranges (cf. Römpp LexikonLacke und Druckfarben, Georg Thieme Verlag, Stuttgart, New York, 1998,“coil coating”, page 55, and “coil coating materials”, page 116).

In order to simplify further the production of motor vehicles from atechnical standpoint, and to make it more economic, it is desired to usepreformed, coated profile elements and moldings for producing vehiclebodies. For this to be possible, however, it is necessary that, with thepreformed, coated profile elements and moldings, further improvements bemade in corrosion protection for the bodies, so that corrosionprotection measures, such as the flooding of cavities with wax, becomesuperfluous. A further requirement is that the corrosion protectionafforded by cathodically deposited and heat-cured electrocoats on coilsbe improved further, or that it be possible to do without theelectrocoats entirely.

Additionally, it is necessary that the coated coils and the profileelements and moldings produced from them, particularly for use in theautomobile sector, can be spot welded.

It is an object of the present invention to provide novel coil coatingmaterials which give coatings possessing extremely high mechanicalintegrity and particularly good corrosion protection, so that it ispossible if necessary to do without cathodically deposited andheat-cured electrocoats. Moreover, it is intended that the particularlygood corrosion protection effect be achievable even without heavymetals. Further, where necessary, the novel coil coating materialsshould be easy to make spot weldable by addition of electricallyconductive pigments without detriment to their other, excellentperformance properties.

The invention accordingly provides the novel corrosion inhibitingmixture comprising

-   (A1) corrosion-inhibiting pigments,-   (A2) amorphous silica modified with metal ions, and-   (A3) at least one compound of the general formula I:    M_(n)(X)_(m)  (I)    -   in which the variables and indices have the following meanings:    -   M is at least one central atom selected from the group of Lewis        acceptors,    -   X stands for Lewis donor ligands having at least one bridging        atom selected from elements of main groups 5 and 6 of the        periodic table of the elements,    -   n is from 1 to 500, and    -   m is from 3 to 2000.

Below, the novel corrosion inhibiting mixture (A) is referred to as“inventive mixture”.

The invention further provides the novel coating materials, especiallycoil coating materials, which comprise the inventive mixture and arereferred to below as “coating materials of the invention”.

In the light of the prior art it was surprising and unforeseeable forthe skilled worker that the object on which the present invention wasbased could be achieved by means of the inventive mixture and by meansof the coating materials of the invention. It was particularlysurprising that the corrosion protection of coils afforded by theinventive mixture was comparable with that of cathodically deposited andheat-cured electrocoats. Even more surprising was that the mixtures ofthe invention could be used together with electrically conductivepigments with no loss of the outstanding corrosion protection in orderto provide for spot weldability of the coatings of the inventionproduced from the coating materials of the invention. Moreover, it waspossible to overcoat the corrosion protection coatings of the inventionwith other coating materials, especially cathodic electrocoat materials,without any problems.

The first essential constituent of the inventive mixture is at least onecorrosion-inhibiting pigment (A1), for which it is possible to use thecustomary and known corrosion-inhibiting pigments. Preferably, thecorrosion-inhibiting pigments (A1) are selected from the groupconsisting of zinc phosphate, zinc metaborate, and barium metaboratemonohydrate, especially zinc phosphate and barium metaboratemonohydrate.

Zinc phosphate is a commercial compound and is sold, for example, underthe brand name Sicor® ZNP/S. Barium metaborate monohydrate is likewise acommercial compound and is sold, for example, under the brand nameButrol® 11M2.

The second essential constituent of the inventive mixture is at leastone amorphous silica (A2) modified with metal ions. Said ions arepreferably selected from the group consisting of alkali metal ions,alkaline earth metal ions, especially calcium ions, scandium ions,yttrium ions and lanthanum ions, lanthanide ions, and zinc ions andaluminum ions. Preference is given to employing calcium ions.

Amorphous silica modified with calcium ions (A2) is also a commercialproduct and is sold, for example, under the brand name Shieldex®.

The third essential constituent of the inventive mixture is at least onecompound of the general formula I. The compounds I can be monomeric(mononuclear) or dimeric, oligomeric or polymeric (polynuclear).

In the general formula I, the variable M stands for at least one centralatom selected from the group of Lewis acceptors. It is preferablyselected from the group consisting of aluminum, titanium, and zirconium.Preferably, M is titanium.

In the general formula I, the variable X stand for Lewis donor ligandshaving at least one bridging atom selected from the elements of maingroups 5 and 6 of the periodic table of the elements. The bridging atomis preferably selected from the group consisting of nitrogen,phosphorus, oxygen, and sulphur atoms, especially phosphorus and oxygenatoms.

Lewis acceptors and Lewis donors are Lewis acids and bases in the senseof the Lewis acid-base theory.

In the general formula I the index n stands for a number, particularlyan integer, from 1 to 500, preferably from 1 to 100, more preferablyfrom 1 to 50, with particular preference from 1 to 20, and in particularfrom 1 to 20. The index m stands for a number, particularly an integer,from 3 to 2000, preferably from 3 to 1000, more preferably from 3 to500, with particular preference from 3 to 100, and in particular from 3to 50.

Examples of highly suitable compounds I are monomeric, dimeric,oligomeric or polymeric alkoxides of aluminum or titanium, such as

-   Al₃(O-tert-butyl)₆,-   Al₄(O-isopropyl)₁₂, or-   Ti(O-ethyl)₄.

Examples of especially suitable compounds of the general formula I arecompounds of the general formula II:RO-M[-O—P(O)(OH)—O—P(O)(OR¹)₂]₃.HP(O)(OR²)₂  (II)in which the variables R, R¹, and R² stand independently of one anotherfor aliphatic and cycloaliphatic radicals and M is as defined above andis selected in particular from the group consisting of aluminum,titanium, and zirconium. With particular preference, M is titanium.

In the general formula II the variables R, R¹, and R² standindependently of one another for aliphatic and cycloaliphatic,especially aliphatic, radicals. The aliphatic radicals preferablycontain from 3 to 20 carbon atoms. Examples of suitable aliphaticradicals are propyl, isopropyl, butyl, sec-butyl, isobutyl, tert-butyl,n-pentyl, isoamyl, n-hexyl, n-heptyl, octyl, isooctyl, nonyl, decyl,undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl,heptadecyl, octadecyl, nonadecyl, and eicosanyl, preferably isopropyl,octyl and isooctyl. With particular preference R is isopropyl, R¹ isoctyl, and R² is isooctyl.

With very particular preference, therefore, use is made of the adduct ofisopropyl tris(dioctylpyrophosphato)titanate with one mole of diisooctylphosphite as constituent (A3). The adduct is a commercial compound andis sold, for example, under the brand name KEN-REACT® by KenrichPetrochemicals.

The weight ratio of the constituents (A1), (A2), and (A3) may varywidely and is guided by the requirements of the case in hand. Preferablythe constituents (A1), (A2), and (A3) are present in a weight ratio of1:(0.5 to 1.5, especially 0.8 to 1.2):(0.1 to 2, especially 0.2 to 0.6).The weight ratio may also be 1:(0.5 to 1.5):(0.2 to 0.6) or 1:(0.8 to1.2):(0.l to 2). With particular preference the weight ratio is 1:(0.8to 1.2):(0.2 to 0.6).

The inventive mixture further comprises at least one electricallyconductive pigment (A4). It preferably has an at least, and especially,bimodal particle size distribution. The electrically conductive pigment(A4) is preferably selected from the group consisting of elementalsilicon and metallic, water-insoluble phosphides, especially consistingof CrP, MnP, Fe₃P, Fe₂P, Ni₂P, NiP₂, and NiP₃. With particularpreference, iron phosphides are employed.

Very particular preference is given to using iron phosphides having abimodal particle size distribution. Particular preference is given tousing a mixture of fine iron phosphides and coarse iron phosphides.Preferably, 90% by weight of the fine iron phosphides have an averageparticle size of from 3 to 16 □m and 90% by weight of the coarse ironphosphides have an average particle size of from 5 to 22 □m. The fineand coarse iron phosphides are used in a weight ratio of preferably from1.4:1 to 1:1.4, more preferably from 1.3:1 to 1:1.3, with particularpreference from 1.2:1 to 1:1.2, and in particular 1:1.

The iron phosphides are commercial products and are sold, for example,under the brand name Ferrophos® (fine: Ferrophos® HRS 2132; coarse:Ferrophos® HRS 2131).

The amount of consistuent (A4) in the inventive mixture may vary widely.The 25 weight ratio of constituents (A1), (A2), and (A3) on the one handto (A4) on the other is preferably from 1:20 to 1:5, more preferablyfrom 1:15 to 1:5, with particular preference from 1:12 to 1:6, with veryparticular preference from 1:10 to 1:7, and in particular from 1:9 to1:7.

The inventive mixtures can be put to a large number of uses. Forinstance, they can be used per se for the corrosion protection ofmoldings made of steel, especially galvanized steel, and aluminum. Theyare preferably used for corrosion protection of coils, preferably coilsof steel, especially galvanized steel, and aluminum.

Alternatively, the inventive mixtures can be added for corrosionprotection purposes to customary and known coating materials. Thesecoating materials can be one-component or multicomponent systems,especially two-component systems. The coating materials of the inventionmay also be formulated on the basis of organic solvents (conventionalcoating materials) or aqueous media (aqueous coating materials).Alternatively, they may be substantially or completely solvent-free andwater-free liquid coating materials (100% systems) or substantially orcompletely solvent-free and water-free, solid, pulverulent coatingmaterials (powder coating materials). The powder coating materials mayalso be in the form of aqueous dispersions, also known as powderslurries.

The coating materials of the invention may be cured thermally, withactinic radiation, or both thermally and with actinic radiation. Hereand below, actinic radiation means electromagnetic radiation, such asnear infrared, visible light, UV radiation or X-rays, especially UVradiation, or corpuscular radiation, such as electron beams. Jointcuring with heat and actinic radiation is also referred to by those inthe art as dual cure.

The resulting coating materials of the invention comprising theinventive mixture can be used for coating motor vehicle bodies and partsthereof, the interior and exterior of motor vehicles, the inside andoutside of buildings, doors, windows, and furniture, and, in the contextof industrial coating, for the coating of small parts, coils,containers, packaging, electrical components, and white goods.

This extremely broad usefulness of the inventive mixture and of thecoating materials of the invention comprising them represents aparticular advantage.

With particular preference, the inventive mixture is added to coilcoating materials. The resulting coatings of the invention may likewisebe one-component or multicomponent, especially two-component, systems;preferably, they are one-component systems. They can be formulated onthe basis of organic solvents or aqueous media. They can also, however,be substantially or completely solvent-free and water-free liquidcoating materials (100% systems) or substantially or completelysolvent-free and water-free powder coating materials. The powder coatingmaterials can also be in the form of powder slurries. With veryparticular preference, conventional coating materials of the inventionare used.

The coating materials of the invention can be cured thermally, withactinic radiation, or both thermally and with actinic radiation. Theyare preferably cured thermally. In this context they may be thermallyself-crosslinking or externally crosslinking. They are preferablyexternally crosslinking.

The amount of the inventive mixture in the coating materials of theinvention may vary widely and is guided by the requirements of the casein hand.

Preferably, the coating materials of the invention contain constituent(A1) in an amount of 0.1 to 10%, more preferably from 0.3 to 8%, withparticular preference from 0.5 to 7%, with very particular preferencefrom 1 to 5%, and in particular from 1.5 to 4% by weight, based in eachcase on the solids of the coating material of the invention.

Preferably, the coating materials of the invention contain constituent(A2) in an amount of 0.1 to 10%, more preferably from 0.3 to 8%, withparticular preference from 0.5 to 7%, with very particular preferencefrom 1 to 5%, and in particular from 1.5 to 4% by weight, based in eachcase on the solids of the coating material of the invention.

Preferably, the coating materials of the invention contain constituent(A3) in an amount of 0.01 to 5%, more preferably from 0.03 to 4%, withparticular preference from 0.05 to 3%, with very particular preferencefrom 0.1 to 2.5%, and in particular from 0.2 to 2% by weight, based ineach case on the solids of the coating material of the invention.

Preferably, within these limits, the above-described advantageous weightratios (A1):(A2):(A3) are set.

Where the coating materials of the invention further compriseconstituent (A4), it is present therein in an amount of preferably from10 to 80%, more preferably from 15 to 75%, with particular preferencefrom 20 to 75%, and in particular from 30 to 75% by weight, based ineach case on the solids of the coating material of the invention. Inthis case it is preferable to use the above-described preferred weightratios of (A1), (A2) and (A3) on the one hand to (A4) on the other.

Besides the inventive mixture, the coating materials of the inventioncomprise constituents such as are customary and known in the field ofcoil coating materials, such as binders, crosslinking agents, organicsolvents, and additives.

The binders are preferably selected from the group consisting of random,alternating, and block, linear, branched, and comb addition (co)polymersof ethylenically unsaturated monomers, polyaddition resins and/orpolycondensation resins which are curable physically, thermally, withactinic radiation, and both thermally and with actinic radiation.Regarding these terms, refer for further details to Römpp Lexikon Lackeund Druckfarben, Georg Thieme Verlag, Stuttgart, New York, 1998, page457, “polyaddition” and “polyaddition resins (polyadducts)”, and pages463 and 464, “polycondensates”, “polycondensation”, and“polycondensation resins”.

The binders are preferably selected from the group consisting of(meth)acrylate addition (co)polymers, partially hydrolyzed polyvinylesters, polyesters, alkyds, polylactones, polycarbonates, polyethers,epoxy resin-amine adducts, polyureas, polyamides, polyimides, andpolyurethanes, especially polyesters.

The preparation of polyesters is described, for example, in the standardwork Ullmanns Encyklopädie der technischen Chemie, 3rd edition, volume14, Urban & Schwarzenberg, Munich, Berlin, 1963, pages 80 to 89 and 99to 105, and also in the following books: “Résines Alkydes-Polyesters” byJ. Bourry, Dunod, Paris, 1952, “Alkyd Resins” by C. R. Martens, ReinholdPublishing Corporation, New York, 1961, and “Alkyd Resin Technology” byT. C. Patton, Interscience Publishers, 1962.

The self-crosslinking binders of the thermally curable coating materialsof the invention and of the dual-cure coating materials of the inventioncontain reactive functional groups which are able to undergocrosslinking reactions with groups of their own kind (“with themselves”)or with complementary reactive functional groups.

The externally crosslinking binders contain reactive functional groupswhich are able to undergo crosslinking reactions with complementaryreactive functional groups that are present in crosslinking agents (cf.Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart, NewYork, 1998, “curing”, pages 274 to 276, especially page 275).

Examples of suitable complementary reactive functional groups for use inaccordance with the invention are assembled in the following overview.In the overview, the variable R⁴ stands for an acyclic or cyclicaliphatic radical, an aromatic radical and/or an aromatic-aliphatic(araliphatic) radical; the variables R⁵ and R⁶ stand for identical ordifferent aliphatic radicals or are linked with one another to form analiphatic or heteroaliphatic ring.

Overview: Examples of Complementary Reactive Functional Groups

Binder and Crosslinking Agent

or

Crosslinking Agent and Binder

—SH —C(O)—OH —NH₂ —C(O)—O—C(O)— —OH —NCO —O—(CO)—NH—(CO)—NH₂—NH—C(O)—OR⁴ —O—(CO)—NH₂ —CH₂—OH >NH —CH₂—OR⁴ —NH—CH₂—OR⁴ —NH—CH₂—OH—N(—CH₂—OR⁴)₂ —NH—C(O)—CH(—C(O)OR⁴)₂ —NH—C(O)—CH(—C(O)OR⁴)(—C(O)—R⁴)—NH—C(O)—NR⁵R⁶ >Si(OR⁴)₂

—C(O)—OH

—N═C═N— —C(O)—N(CH₂—CH₂—OH)₂

The selection of the respective complementary groups is guided on theone hand by the consideration that they should not undergo any unwantedreactions, particularly no premature crosslinking, during thepreparation, storage, and application of the coating materials of theinvention and/or must not disrupt or inhibit, where appropriate, theactinic radiation cure, and on the other hand by the temperature rangewithin which crosslinking is to take place.

For the coating materials of the invention it is preferred to employcrosslinking temperatures of up to 270° C. Preference is therefore givento employing thio, hydroxyl, N-methylolamino, N-alkoxymethylamino,imino, carbamate, allophanate and/or carboxyl groups, preferablyhydroxyl or carboxyl groups, on the one hand and, preferably,crosslinking agents containing anhydride, carboxyl, epoxy, blockedisocyanate, urethane, methylol, methylol ether, siloxane, carbonate,amino, hydroxyl and/or beta-hydroxyalkylamide groups, preferably epoxy,beta-hydroxyalkylamide, blocked isocyanate, urethane oralkoxymethylamino groups, on the other.

In the case of self-crosslinking coating materials of the invention thebinders contain in particular methylol, methylol ether and/orN-alkoxymethylamino groups.

Complementary reactive functional groups especially suitable for use inthe externally crosslinking coating materials of the invention are

-   carboxyl groups on the one hand and epoxide groups and/or    beta-hydroxyalkylamide groups on the other, and also-   hydroxyl groups on the one hand and blocked isocyanate, urethane or    alkoxymethylamino groups, especially blocked isocyanate groups, on    the other.

The functionality of the binders in respect of the reactive functionalgroups described above may vary very widely and is guided in particularby the target crosslinking density and/or by the functionality of theparticular crosslinking agents employed. In the case ofcarboxyl-containing binders, for example, the acid number is preferablyfrom 10 to 100, more preferably from 15 to 80, with particularpreference from 20 to 75, with very particular preference from 25 to 70,and in particular from 30 to 65 mg KOH/g. Or, in the case ofhydroxyl-containing binders, the OH number is preferably from 15 to 300,more preferably from 20 to 250, with particular preference from 25 to200, with very particular preference from 30 to 150, and in particularfrom 35 to 120 mg KOH/g. Or, in the case of binders containing epoxidegroups, the epoxide equivalent weight is preferably from 400 to 2500,more preferably from 420 to 2200, with particular preference from 430 to2100, with very particular preference from 440 to 2000, and inparticular from 440 to 1900.

The complementary functional groups described above can be incorporatedinto the binders by the customary and known methods of polymerchemistry. This can be done, for example, by incorporating monomerswhich carry the corresponding reactive functional groups, and/or bymeans of polymer-analogous reactions.

The binders of the dual-cure coating materials of the invention and ofthe coating materials of the invention that are curable with actinicradiation alone further contain on average per molecule at least one,preferably at least two, group(s) having at least one bond which can beactivated with actinic radiation.

In the context of the present invention, a bond which can be activatedwith actinic radiation is a bond which, on exposure to actinicradiation, becomes reactive and, with other activated bonds of its kind,undergoes polymerization reactions and/or crosslinking reactions whichproceed in accordance with radical and/or ionic mechanisms. Examples ofsuitable bonds are carbon-hydrogen single bonds or carbon-carbon,carbon-oxygen, carbon-nitrogen, carbon-phosphorus or carbon-siliconsingle bonds or double bonds.

In the dual-cure coating materials of the invention it is, however, alsopossible to employ mixtures of binders curable by means of heat aloneand binders curable solely with actinic radiation.

The amount of the above-described binders in the coating materials ofthe invention may vary widely and is guided by the requirements of thecase in hand, in particular by the functionality of any crosslinkingagents used. Preferably, the binders are employed in an amount so as togive a pigment/binder ratio >2.4:1, more preferably >2.6:1, and withparticular preference >2.8:1. With very particular preference thepigment/binder ratio is from 2.9:1 to 3.2:1.

Examples of suitable crosslinking agents are amino resins, as described,for example, in Römpp Lexikon Lacke und Druckfarben, Georg ThiemeVerlag, 1998, page 29, “amino resins”, in the textbook “Lackadditive”[Additives for coatings] by Johan Bieleman, Wiley-VCH, Weinheim, N.Y.,1998, pages 242 ff., in the book “Paints, Coatings and Solvents”,second, completely revised edition, edited by D. Stoye and W. Freitag,Wiley-VCH, Weinheim, N.Y., 1998, pages 80 ff., in the patents U.S. Pat.No. 4,710,542 A1 or EP-B-0 245 700 A1, and in the article by B. Singhand coworkers “Carbamylmethylated Melamines, Novel Crosslinkers for theCoatings Industry”, in Advanced Organic Coatings Science and TechnologySeries, 1991, volume 13, pages 193 to 207, compounds or resinscontaining carboxyl groups, as described, for example, in the patent DE196 52 813 A1, compounds or resins containing epoxide groups, asdescribed, for example, in the patents EP 0 299 420 A1, DE 22 14 650 B1,DE 27 49 576 B1, U.S. Pat. No. 4,091,048 A1 or U.S. Pat No. 3,781 379A1, nonblocked and blocked polyisocyanates, as described, for example,in the patents U.S. Pat. No. 4,444,954 A1, DE 196 17 086 A1, DE 196 31269 A1, EP 0 004 571 A1 or EP 0 582 051 A1, and/ortris(alkoxycarbonylamino)triazines, as described in the patents U.S.Pat. No. 4,939,213 A1, U.S. Pat. No. 5,084,541 A1, U.S. Pat. No.5,288,865 A1 or EP0604 922 A1.

With particular preference, blocked polyisocyanates are used. Inparticular, use is made of the polyisocyanates blocked with the blockingagents known from the German patent application DE 199 14 896 A1, column12 line 13 to column 13 line 2, especially polyisocyanates blocked withcaprolactam.

The amount of the crosslinking agent in the coating materials of theinvention may vary widely and is guided by the requirements of the casein hand, in particular by the functionality of the binders used.

Particular preference is given to using one-component systems composedof hydroxyl-containing polyesters and caprolactam-blockedpolyisocyanates. These one-component systems are commercial products andare sold, for example, under the brand name Vesticoat® EPUB 877.

The amount of crosslinking agents and binders in the coating materialsof the invention is preferably from 10 to 60%, more preferably from 12to 55%, with particular preference from 15 to 50%, and in particularfrom 15 to 45% by weight, based in each case on the solids of thecoating material of the invention.

The coating material of the invention may comprise an organic solvent.Examples of customary and known solvents are described in D. Stoye andW. Freitag (eds.), “Paints, Coatings and Solvents”, 2nd, completelyrevised edition, Wiley-VCH, Weinheim, N.Y., 1998, “14.9. SolventGroups”, pages 327 to 373. In the coating material of the invention theyare used preferably in an amount of from 5 to 50% by weight, inparticular from 5 to 40% by weight, based on the coating material of theinvention.

The coating material of the invention not least comprises at least onetypical coatings additive selected from the group consisting ofinorganic and organic additives.

Examples of suitable typical coatings additives are color and/or effectpigments, fillers, nanoparticles, reactive diluents for the thermal cureor the actinic radiation cure, rheological aids, UV absorbers, lightstabilizers, radical scavengers, radical polymerization initiators,thermal crosslinking catalysts, photoinitiators and photocoinitiators,slip additives, polymerization inhibitors, defoamers, emulsifiers,devolatilizers, wetting agents, dispersants, adhesion promoters,leveling agents, film forming auxiliaries, rheology control additives(thickeners), flame retardants, siccatives, driers, antiskinning agents,other corrosion inhibitors, waxes, and flatting agents, such as areknown from the textbook “Lackadditive” by Johan Bieleman, Wiley-VCH,Weinheim, N.Y., 1998, or the German patent application DE 199 14 896 A1,column 13 line 56 to column 15 line 54.

Examples of especially suitable additives are silylamines, such asbis(trimethylsilyl)amine, which is sold under the brand name Aerosil®812 S, epichlorohydrins, such as bisphenol A epichlorohydrin, which issold under the brand name Epikote® 834, a self-crosslinking urethaneresin, which is sold under the brand name Desmodur® VPLS 2253, anddibutyltin dilaurate.

The preparation of the coating materials of the invention has no specialfeatures as far as its method is concerned but instead takes place bythe mixing of the constituents described above. This can be done usingmixing equipment such as stirred tanks, dissolvers, including inlinedissolvers, bead mills, stirrer mills, static mixers, toothed wheeldispersers or extruders. Where appropriate, it is carried out withexclusion of actinic radiation in order to prevent damage to the coatingmaterial of the invention which is curable solely or additionally withactinic radiation. In the course of preparation, the individualconstituents of the inventive mixture can be incorporated separately.Alternatively, the inventive mixture can be prepared separately andmixed with the other constituents. Preferably, the individualconstituents of the inventive mixture are incorporated separately.

The coating materials of the invention are outstandingly suitable forcoil coating. Coil coating starts from a coil of metal which hasconventionally been cleaned, degreased, passivated, chemically treated,rinsed, and dried. The metal coil can be coated on one or both sides.

Suitable metals are all those from which it is possible to form coilswhich are equal to the mechanical, chemical, and thermal stresses ofcoil coating. Highly suitable metal coils are those based on aluminum oriron. In the case of iron, cold-rolled steels, electrolyticallyzinc-plated steels, hot-dip galvanized steels, or stainless steels areespecially suitable. Preferably, the metal sheets of the coils have athickness of from 200 μm to 2 mm.

For coil coating, the metal coil passes through a coil coating line,such as is described, for example, in Römpp Lexikon Lacke undDruckfarben, Georg Thieme Verlag, Stuttgart, N.Y., 1998, page 55, “coilcoating”, or in the German patent application DE 196 32 426 A1, at aspeed adapted to the application and curing properties of the coatingmaterials of the invention that are employed. The speed may thereforevary very widely from one coating process to another. It is preferablyfrom 10 to 150, more preferably from 12 to 120, with particularpreference from 40 to 100, with very particular preference from 16 to80, and in particular from 20 to 70 m/min.

The coating materials of the invention may be applied in any desiredmanner; for example, by spraying, flowcoating or roller coating. Ofthese application techniques, roller coating is particularlyadvantageous and is therefore used with preference in accordance withthe invention.

Each application step in roller coating may be conducted using two ormore rolls. Preference is given to the use of from two to four, andespecially two, rolls.

In roller coating, the rotating pickup roll dips into a reservoir of thecoating material of the invention and so picks up the coating materialto be applied. This coating material is transferred by the pickup roll,directly or via at least one transfer roll, to the rotating applicationroll. From this latter roll, the coating material is transferred ontothe coil by means of codirectional or counterdirectional contacttransfer.

Alternatively, the coating material of the invention may be pumpeddirectly into a gap or nip between two rolls, this being referred to bythose in the art as nip feed.

In accordance with the invention, counterdirectional contact transfer,or the reverse roller coating process, is of advantage and is thereforeemployed with preference.

In roller coating, the peripheral speeds of the pickup roll andapplication roll may vary very greatly from one coating process toanother. The application roll preferably has a peripheral speed which isfrom 110 to 125% of the coil speed, and the pickup roll preferably has aperipheral speed which is from 20 to 40% of the coil speed.

The coating materials of the invention are preferably applied in a wetfilm thickness such that curing of the coating films results incorrosion protection coatings which have a dry film thickness of from 4to 12 μm, more preferably from 5 to 10 μm, with particular preferencefrom 5 to 9.5 μm, and in particular from 6 to 9 μm.

The application methods described above can be employed with the coatingmaterials with which the corrosion protection coatings of the inventionare overcoated, except where they are powder coating materials orelectrocoat materials, for which the customary and known, specialapplication methods are used, such as electrostatic powder spraying inthe case of low-speed coils or the powder cloud chamber process in thecase of high-speed coils, and cathodic electrodeposition coating.

In the case of heat curing, heating of the coating films of theinvention takes place preferably by means of convective heat transfer,irradiation with near or far infrared and/or, in the case of iron-basedcoils, by means of electrical induction. The maximum substratetemperature is preferably 270° C. and in particular 260° C.

The heating time, i.e., the duration of the heat cure, varies dependingon the coating material of the invention that is used. It is preferablyfrom 10 s to 2 min.

Where use is made substantially of convective heat transfer, forced airovens with a length of from 30 to 50 m, in particular from 35 to 45 m,are required at the preferred coil running speeds. The temperature ofthe forced air is preferably 350° C.

Thermal curing of the coating films of the invention may also beassisted by exposure to actinic radiation.

Alternatively, curing may take place with actinic radiation alone, as isdescribed, for example, in the German patent application DE 198 35 206A1.

Curing with actinic radiation is carried out using the customary andknown radiation sources and optical auxiliary measures. Examples ofsuitable radiation sources are flashlights from the company VISIT, highor low pressure mercury vapor lamps, which may have been doped with leadin order to open a radiation window of up to 405 nm, or electron beamsources. The arrangement of these sources is known in principle and canbe adapted to the circumstances of the workpiece and the processparameters.

The curing methods described above can of course also be used for thecoating films with which the corrosion protection coatings of theinvention are overcoated.

If two or more coating materials are applied during the coil coatingoperation, this is carried out in an appropriately configured line, inwhich two or more application and, where appropriate, curing stationsare interposed in series. Alternatively, following application andcuring of the first coating material, i.e., the coating material of theinvention, the coated coil is wound up again and is then provided on oneor both sides with second, third, etc. coatings in a second, third, etc.coil coating line.

Following the production of the coated coils, they can be wound up andthen processed further at another place; alternatively, they can beprocessed further as they come directly from the coil coating operation.For instance, they may be laminated with plastics or provided withremovable protective films. After cutting into appropriately sizedparts, they may be shaped. Examples of suitable shaping methods includepressing and deep drawing.

The resultant coils, profile elements, and moldings are scratchresistant, stable to corrosion, weathering, and chemicals, and can beovercoated with any of a wide variety of coating materials, withoutproblems. It is surprising that there is no need for chromatepretreatment of the metal coils in order to obtain excellent corrosionprotection.

The coils coated with the corrosion protection coatings of the inventionare therefore outstandingly suitable for applications in automotiveconstruction for the purpose, for example, of producing bodywork partsand bodies, truck bodies, and caravan paneling, in the householdappliance sector for producing, for example, washing machines,dishwashers, driers, fridges, freezers or ranges, in the lighting sectorfor producing lights for interior and exterior use, or in the interiorand exterior architectural sector, for producing, for example, ceilingand wall elements, doors, gates, pipe insulation, roller shutters orwindow profiles.

EXAMPLES Example 1 The Preparation of the Inventive Coil CoatingMaterial 1

In a suitable vessel with stirrer, the following components were mixedin this order: 26.9 parts by weight of a one-component system based on asaturated, hydroxyl-containing polyester and a caprolactam-blockedpolyisocyanate (Vesticoat® EPUB 877 from Hüls AG), 0.6 part by weight ofbis(trimethylsilyl)amine (Aerosil® R 812 S from Degussa), 2.47 parts byweight of silica modified with calcium ions (Shieldex® from GraceDavison), 2.73 parts by weight of zinc phosphate (Sicor® ZNP/S fromWaardals Kjemiske Fabriken), 0.99 part by weight of the adduct ofisopropyl tris(dioctylpyrophosphato)titanate with one mol of diisooctylphosphite (KEN-REACT® KR38S from Kenrich Petrochemicals), and 4.5 partsby weight of Solvesso® 150 (ExxonMobil Chemicals). This mixture waspredispersed using a dissolver for ten minutes. The resulting mixturewas transferred to a bead mill with a cooling jacket, and was mixed with2 mm SAZ glass beads. The material for milling was milled for 12 minutesto a Hegmann particle size of from 10 to 15 μm. The resulting millbasewas then separated from the glass beads.

To the millbase there were added, with stirring, in this order, 3.55parts by weight of bisphenol A epichlorohydrin (Epikote® 834 from ShellResins), 1.78 parts by weight of a commercial self-crosslinking urethaneresin (Desmodur® VPLS 2253 from Bayer AG), 0.1 part by weight ofdibutyltin dilaurate, and 4.26 parts by weight of Solvesso® 150.

With the dissolver running slowly, the resultant mixture was admixedwith 52.6 parts by weight of iron phosphide (Ferrophos® HRS 2131 fromNordmann Rasmann). After a further ten minutes, the desired dispersionof the electrically conductive pigments was reached.

The inventive coil coating material 1 was outstandingly suitable for thecoil coating process.

Example 2 The Preparation of the Inventive Coil Coating Material 2

Example 1 was repeated but using barium metaborate monohydrate (Butrol®11 M2 from Buckman) instead of zinc phosphate.

Examples C1 and C2 (Comparative) The Preparation of the NoninventiveCoil Coating Materials C1 and C2

Examples 1 and 2 were repeated but using KEN-REACT® KR38S in neithercase.

Examples 3, 4, C3, and C4 The Production of Inventive (Examples 3 and 4)and Noninventive (Examples C3 and C4) Corrosion Protection Coatings

For example 3, the inventive coil coating material 1 was used.

For example 4, the inventive coil coating material 2 was used.

For example C3, the noninventive coil coating material C1 was used.

For example C4, the noninventive coil coating material C2 was used.

Using coating rods, the coil coating materials were applied to steelplates of grades Z and ZE with chromate-free pretreatment, in a wet filmthickness such that curing thereof in a through-type drier with aforced-air temperature of 350° C. and a substrate temperature of 220° C.gave corrosion protection coatings having a dry film thickness of 8 □m.

The steel plates with the corrosion protection coatings were subjectedto the VDA [German automakers association] alternating climate test for20 days. Measurements were then made of the minimum and maximum incisioncreep and scribe creep, and of the white rust and red rust. The tablegives an overview of the results obtained. The results demonstrate theexcellent corrosion protection afforded by the inventive corrosionprotection coatings of examples 3 and 4. The white rust and red rustpercentages refer to the surface areas of the steel plates affected byrust.

TABLE The corrosion protection effect of the inventive corrosionprotection coatings of examples 3 and 4 and of the non- inventivecorrosion protection coatings of examples C3 and C4 after the VDAalternating climate test Example and Creep (mm) comparative(minimum/maximum) White rust Red rust example incision scribe (%) (%) C35/7 1.5/4   30 30 C4 5/8 1.5/4   30 40 3 2/6   0/0.5 5 30 4 2/6   0/0.50 25

1. A corrosion inhibiting mixture comprising (A1) at least onecorrosion-inhibiting pigment, (A2) amorphous silica modified with metalions, and (A3) at least one compound of the general formulaRO-M[-O—P(O)(OH)—O—P(O)(OR¹)₂]₃.HP(O)(OR²)₂ in which the variables andindices have the following meanings: R is a first aliphatic orcycloaliphatic radical; R¹ is a second aliphatic or cycloaliphaticradical; R² is a third aliphatic or cycloaliphatic radical; M is atleast one central atom selected from the group of Lewis acceptors; andR, R¹, and R² are different.
 2. The mixture of claim 1, wherein the atleast one corrosion-inhibiting pigment (A1) is selected from the groupconsisting of zinc phosphate: zinc metaborate, and barium metaboratemonohydrate.
 3. The mixture of claim 1, wherein the metal ions in thecompound (A2) are selected from the group consisting of alkali metalions, alkaline earth metal ions, scandium ions, yttrium ions, lanthanumions, and lanthanide ions, and zinc ions and aluminum ions.
 4. Themixture as claimed in claim 3, wherein the metal ions are calcium ions.5. The mixture of claim 1, wherein the central atom M in the compound(A3) is selected from the group consisting of aluminum, titanium, andzirconium.
 6. The mixture as claimed in claim 5, wherein M is titanium.7. The mixture of claim 1, wherein the constituents (A1). (A2), and (A3)are in a weight ratio of 1:(0.5 to 1.5):(0.1 to 2).
 8. The mixture ofclaim 1 further comprising at least one electrically conductive pigment(A4).
 9. The mixture as claimed in claim 8, wherein said electricallyconductive pigment (A4) has an at least bimodal particle sizedistribution.
 10. The mixture of claim 8, wherein said electricallyconductive pigment (A4) is selected from the group consisting ofelemental silicon and metallic, water-insoluble phosphides.
 11. Acoating material comprising the corrosion inhibiting mixture of claim 1.12. The coating material of claim 11, wherein constituent (A1) ispresent in an amount of from 0.1 to 10% by weight, based on the solidsof the coating material.
 13. The coating material of claim 11, whereinconstituent (A2) is present in an amount of from about 0.1 to 10% byweight, based on the solids of the coating material.
 14. The coatingmaterial of claim 11, wherein constituent (A3) is present in an amountof from 0.01 to 5% by weight, based on the solids of the coatingmaterial.
 15. The coating material of claim 11 further comprising atleast one electrically conductive pigment (A4) in an amount of from 10to 80% by weight, based on the solids of the coating material.
 16. Thecoating material of claim 15, wherein the weight ratio of constituent(A4) on the one hand to constituents (A1), (A2), and (A3) on the otheris from 20:1 to 5:1.
 17. The coating material of claim 11, wherein thecoating material is a one-component system.
 18. The coating material ofclaim 11, wherein the coating material is curable thermally, withactinic radiation, or both thermally and with actinic radiation.
 19. Thecoating material of claim 11, wherein the coating material one of asolvent containing coating material; an aqueous coating material; asolvent-free and water-free liquid coating material; a solvent-free, andwater-free, solid pulverulent coating material; or an aqueous dispersionof a powder coating material.
 20. The coating material of claim 11,wherein the coating material is a coil coating material.